Surinder Sud: Why every insect is not a pest

It is a myth that most insects are harmful and thus, need to be dreaded and destroyed. In reality, only a fraction of all insects, less than five per cent, are hazardous for crops, animals or human beings. Most others are either harmless or useful for agriculture, commerce, or ecology. In agriculture, insects play a vital role as pollinators, to boost crop yields or as natural foes of destructive pests, to serve as biological pest control agents. Valuable commercial products such as honey, silk fibre and lac are produced by insects. Some insects act as indicators of the state of environment degradation. And most interestingly, several types of insects are consumed as nutritious food by tribal communities in many parts of the world, including the north-eastern states in India.

Though efforts to develop a database of insects with their nomenclature and characteristics have been underway for centuries, most insects remain undiscovered and undocumented. According to Bangalore-based National Bureau of Agriculturally Important Insects (NBAII) Director Abraham Verghese, there appear to be about 160,000 of these six-legged creatures. Of this, only about 60,000 have been traced, and scientifically named and classified. Hardly 2,000-odd insects can be viewed as pests since they damage the crops or hurt livestock and human beings as vectors of viruses or other disease-causing pathogens. The only worry is that the number of such pests may swell menacingly, given that many existing or new insects are transforming into pests due to climate change, loss of habitat and the worsening natural balance of wild fauna.

The NBAII, which has been mandated to search for, classify and name unknown insects, plans to organise exploratory expeditions of the kind undertaken by Charles Darwin, who conceived the theory of origin of species. The current day explorers, of course, have the advantage of being equipped with modern information and biotechnological tools that Darwin lacked. Their ventures are expected to substantially enrich the available database of insects. A beginning has already been made with the discovery of about 475 new insects in the recent past.

The NBAII has set three major goals before itself. One, collect and maintain specimens of insects, so that entomologists from around the globe can examine and study them. Two, build a digitised and barcoded repository of insects for the benefit of researchers and others. And three, maintain germplasm of various kinds of insects, including mites, spiders and nematodes. This virtual gene bank of insects currently hosts live cultures of over 100 insect species. This unique facility is proposed to be expanded fivefold to hold around 500 live insect cultures by 2050. "This is likely to emerge as the most sought-after repository of Oriental insects for the world's entomologists," maintains Verghese. Ironically, many of the previous collections of insects of agricultural or economic importance are found in museums outside India, notably in the Natural History Museum, London, for want of such facilities here.

Entomologists involved in finding, preserving and studying unknown insects hope to come across numerous new creatures that may have useful traits such as the ability to check proliferation of perilous pests in an environmentally safe manner. Some insects-based means of pest control are already being gainfully used to manage various dreaded pests, such as mealy bugs of papaya, gall wasps of eucalyptus, woolly aphids of sugarcane and stem or leave borers of rice and sugarcane. A few exotic insects, too, have been effectively utilised to curb some highly resilient terrestrial and aquatic weeds and pests, such as Parthenium (commonly known as Congress grass), water hyacinth and whitefly (that prompted the European Union to ban mango imports from India). Further progress in this field would diminish the dependence on costly pesticides to combat pests.

This apart, the work in the field of agriculturally important insects is expected to remove some glaring lacunae like the dearth of trained people and repositories of insect specimens. There is a need to equip selected Krishi Vigyan Kendras with skilled manpower and facilities to multiply useful insects like pollinators and predators, and release them in the fields for the benefit of farmers.

surinder.sud@gmail.com

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Surinder Sud: Why every insect is not a pest